DESCRIPTION: (Adapted from the application) The main goal of the proposed research is to develop a comprehensive mathematical model of the cochlea mechanics and to use it for the simulation of pathological changes in human hearing related to aging. The project has three specific aims. Specific Aim 1 is to develop a comprehensive model of passive and active properties of the outer hair cell. The model of outer hair cell will include its passive viscoelastic properties determined by the characteristics of the basic subcellular elements (plasma membrane, cortical lattice, and subsurface cisternae). A nonlinear model of active properties of outer hair cell will be based on observation of its electromotility. Experimental data on viscoelasticity and electromotility of outer hair cell obtained as a result of collaboration with experimental groups of Dr. W.E. Brownell (Baylor College of Medicine) and Dr. R.J. Hallworth (Texas Medical Center) will be used for the outer hair cell model. Specific Aim 2 is to develop a model of the mechanics of the organ of Corti and integrate it into a model of the intact cochlea. A model of the organ of Corti will include viscoelastic and inertial properties of the basilar membrane, the tectorial membrane, outer hair cell, the stereocilia and their nonlinear interactions. The applicant will use a known approach to the modeling of the intact cochlea with specific terms of the forces acting on the basilar membrane. These terms are determined from their models of outer hair cell and the organ of Corti. Specific Aim 3 is the modeling of the aging effects. They will use their model for simulation of major pathological factors that have been observed in the aging cochlea; among such factors are the total number of outer hair cells, their distribution along the cochlea, degeneration of the stereocilia, and changes of the outer hair cell properties. They will analyze the effects of these factors by studying the resonant curves of the basilar membrane. The proposed research should provide a fast and accurate interpretation of experimental and clinical data, and may help in developing cochlea implants and effective treatment of the hearing loss in the elderly.